OC02.05: Angiogenic factors versus Doppler in term FGR and SGA

Among small fetuses, two conditions can be distinguished by Doppler ultrasound: small for gestational age (SGA) and fetal growth restriction (FGR). Angiogenic factors, such as the soluble fms-like tyrosine kinase-1 to placental growth factor ratio (sFlt-1/PlGF), have been shown to be non-inferior to fetomaternal Doppler ultrasound in avoiding adverse perinatal outcomes in all small fetuses after 36 weeks of gestation. Our aim was to confirm these findings separately for FGR and SGA. We conducted a secondary analysis of data from the GRAFD Trial: a multicentre, open-label, randomised, non-inferiority, controlled trial across 20 maternity centres in Spain. The trial was registered at ClinicalTrials.gov, number NCT04502823 on August 6, 2020. We enrolled single pregnancies with an estimated fetal weight ≤10th percentile between 36 weeks and 37 weeks and 6 days. Participants were randomly assigned in a 1:1 ratio to either a Doppler-based protocol (control group) or an sFlt-1/PlGF-based protocol (intervention group). Non-inferiority was achieved if the upper limit of the 95% confidence interval for the difference in adverse perinatal outcome incidences between the groups was less than 8.5%. Cases with an estimated fetal weight <3rd percentile or with abnormal Doppler studies were classified as FGR; otherwise, they were classified as SGA. Between September 28, 2020, and November 30, 2022, a total of 1,013 participants were recruited. Among them, 409 were classified as FGR (201 in the intervention group and 208 in the control group), and 604 were classified as SGA (312 in the intervention group and 292 in the control group). The rates of adverse perinatal outcomes were similar between the groups for both FGR (absolute difference, -0.01 [-6.7 to 6.7]) and SGA (absolute difference, 1.14 [-3.1 to 5.4]), confirming the non-inferiority of the sFlt-1/PlGF ratio in avoiding adverse perinatal outcomes. The sFlt-1/PlGF ratio is non-inferior to fetomaternal Doppler ultrasound for avoiding adverse perinatal outcomes in SGA and FGR after 36 weeks of gestation.